This invention pertains to a control system for a refrigeration system, and more particularly to a system particularly adaptable for controlling a refrigeration system used for cooling freezer cases and compartments typically employed in supermarkets, and for supplying an alarm indication upon the temperature in the freezer case reaching an alarm condition stage.
Typically, bimetal switches or sensors are employed for controlling the refrigeration system of a supermarket freezer case. The bimetal switches are adjusted at preselected temperatures to define an upper and lower range of temperatures within which it is desired to maintain the freezer compartment temperature. When the freezer compartment temperature reaches the upper limit, a refrigeration control valve is opened to supply an additional amount of refrigeration fluid to the evaporator radiator located in the freezer compartment. When the temperature drops to the lower limit of the desired range, the valve is closed. Because bimetallic switches do not typically respond in a reliable and consistent manner to the freezer case temperature, it is necessary to set the upper and lower limits of the desired range unnecessarily low to assure that the refrigeration system will respond as is desired. As a result of the unnecessary low settings, the temperature in the freezer case is usually maintained lower than necessary to preserve the items in the freezer case, and the amount of energy consumed by the refrigeration system in cooling the compartment is increased. In addition, the additional cooling capacity required of the refrigeration system necessitates that the compressor and other elements of the system be of an increased capacity. It is to these and other problems in this field that the present invention is addressed.